The goal of this proposal is to understand the mechanisms by which mammalian cells regulate the synthesis of specific proteins in response to specific stimuli. Our studies will focus on a major acute phase protein, the serum amyloid P component (SAP). This protein has been preserved through evolution and has kept its binding activities and structure. It is a constitutive protein in humans. Yet it is a major acute phase protein in mice. It is also identical to the tissue amyloid P component (AP), a constituent of all kinds of amyloid depositis. The objectives of this work are: 1) to study the synthesis and the post-translational processing of SAP and to identify mediators the induce its synthesis, 2) to isolate and characterize the human and mouse SAP gene(s) and find the sites of their expression under resting and acute phase conditions, and 3) to identify regulatory regions of the human and mouse SAP gene which determine their response to acute phase stimuli and study the regulation of expression of the cloned SAP genes following transfection of mouse L cells and of human hepatoma Hep3B cells. The synthesis and post-translational processing of human and mouse SAP will be studied in xenopus oocytes, hepatoma cell line, (HepG2), and in primary cultures of mouse hepatocytes. The human and mouse SAP genes will be isolated from genomic libraries using the human cDNA SAP clone as hybridization probe. The sites of mouse gene expression, under normal and acute phase conditions, will be determined by blotting analysis of RNA isolated from various mouse tissues and by organ cultures of tissue specimens. The human and the mouse SAP genes will be compared by computer analysis. This analysis may reveal homologous noncoding regions of the genes which control their expression. The functional significance of these sequences in the expression of SAP will be studied using eucaryotic gene expression systems. These studies will elucidate the structure of SAP gene(s) and the corresponding protein(s). They will provide insight into the regions that control the expression of the genes as well as the stimuli that may trigger SAP expression. Since SAP expression is associated with the development of amyloidosis, which complicates diseases as arthritis in children and adults, the contol of the expression of these genes may prove to be important for the prevention of this abnormal and irrevesible condition.